I. Overview
Subacute thyroiditis, referred to as subacute thyroiditis, was first discovered and described in 1904 and is also known as granulomatous thyroiditis, giant cell thyroiditis, etc. It is a relatively common self-limiting inflammatory thyroid disease that has been on the rise in recent years. The onset of the disease is mostly in summer and spring, and is more common in young and middle-aged women, with a female incidence three to five times higher than that of men, and a high incidence age of 30 to 50 years.
Etiology
The cause of this disease is unknown, and it is generally believed to be related to viral infections. Most patients develop the disease 1 to 4 weeks after upper respiratory tract infection. At the onset of the disease, patients have elevated titers of antibodies to certain viruses, including coxsackievirus, adenovirus, influenza virus, and mumps virus. When mumps is endemic, it can also cause epidemic thyroiditis, where patients have high titers of mumps virus antibodies in their sera. Immune mechanisms have also been reported to be involved in the development of the disease. Destruction of thyroid follicular epithelial cells and loss of follicular integrity are the major pathophysiological findings of the disease.
Clinical manifestations
The clinical manifestations of subxiphoid nail infection are complex and diverse, and often overlap with those of other thyroid disorders, leading to misdiagnosis and misdiagnosis. The typical manifestations are neck pain, thyroid tenderness and other systemic symptoms. The disease is often divided into acute, remission and recovery phases according to its development.
1. Acute phase: Typical patients have an acute onset with chills, fever, sore throat and other upper respiratory symptoms, followed by painful enlargement of the thyroid gland, starting with one side of the thyroid and then expanding to the other. It may start on one side of the thyroid gland and then expand to the other side, followed by involvement of the entire thyroid gland. The thyroid gland is mostly nodular, hard and can move up and down with swallowing movements. When the pain is severe, it can radiate along the neck to the jaw, behind the ear, occipital area, gums, chest and back, etc. The pain increases when chewing, swallowing, eating, coughing, turning the neck or lowering the head. Patients in the acute stage tend to show signs of hyperthyroidism, such as fear of heat and sweating, palpitations, excessive food and hunger, increased frequency of stools, weight loss, nervousness, irritability, and hand tremors. Physical examination reveals mild to moderate enlargement of the thyroid gland, sometimes unilateral enlargement is obvious, hard texture, significant tenderness, and a few patients have enlarged lymph nodes in the neck.
2. Remission phase: The disease is mostly self-limiting, mostly lasting for weeks to months in complete remission, and in a few patients it can be prolonged for 1 to 2 years. Most patients do not have hypothyroidism when they enter the remission phase. After experiencing hyperthyroidism, they enter the recovery phase directly from the transition phase; a few patients may have hypothyroidism, and patients often have hypothyroidism, such as fatigue, lethargy, drowsiness, fear of cold and warmth, pallor, loss of appetite, bloating and constipation, swelling, and weight gain. This is due to the destruction of thyroid cells due to inflammation and the gradual depletion of thyroid hormones.
3.Recovery period: Goiter and nodules gradually disappear, or small nodules may remain, which are slowly absorbed later. If the treatment is timely, the patient can mostly recover completely. Some studies have shown that the occurrence of hypothyroidism is more common in the first year of the onset of subthyroiditis, but only about 5% of patients become permanently hypothyroid. With regular treatment, subluxation is less likely to recur. Studies have shown that about 1.4 to 4% of patients relapse after several years of treatment.
4. Atypical manifestations: Atypical manifestations of this disease are not uncommon, and are mostly manifested as follows: enlarged thyroid gland and/or thyroid nodules often without obvious conscious pain or tenderness, or without history of upper respiratory tract infection, mild systemic symptoms, no obvious hyperthyroidism or hypothyroidism manifestations, and in a few cases, the thyroid gland nodules are first manifested rather than diffusely enlarged, without obvious pressure pain, and may be without systemic fever symptoms. At this time, we need to carefully inquire about the process of onset and treatment, and improve the relevant tests to clarify.
Routine examination
1.Thyroid function test
Due to the destruction of thyroid follicular cells, thyroid hormones and abnormal iodide substances are released from the follicles into the blood, causing an increase in serum T4 and T3, resulting in clinical hyperthyroidism and inhibition of TSH secretion. Due to the destruction of follicular epithelial cells, TSH cannot increase the uptake of radioactive iodine by thyroid follicular epithelial cells, resulting in a reduced rate of radioactive iodine uptake by the thyroid gland. Therefore, although serum TT3, TT4, FT3 and FT4 are elevated and TSH secretion is suppressed in the hyperthyroid phase, the thyroid uptake rate of 131I is low and the thyroid nuclear scan is unremarkable or unremarkable, showing the so-called “separation phenomenon”. In the later stages of the disease, as the hormones stored in the follicles have been drained, serum T4 and T3 concentrations gradually decline, sometimes to hypothyroid levels, and TSH rises, often above normal. During the recovery period, serum T3/T4, TSH and 131I uptake rates return to normal. In some cases, the destruction of thyroid follicular cells is not severe, and serum T3, T4 and TSH may be within normal range, so they may not show the above changes.
2.Blood sedimentation
Blood sedimentation increases significantly, mostly ≥40mm/h, up to 100mm/h. As the condition improves, blood sedimentation gradually returns to normal, and normal blood sedimentation can be used as an indicator of drug reduction.
3.Blood routine
White blood cells are mildly to moderately elevated, neutrophils are normal or slightly elevated, and lymphocyte count may be elevated, but it is not specific.
4. If thyroid isotope scan is performed, the acute phase is mostly cool nodules, cold nodules or completely unremarkable
As the disease improves, the iodine uptake rate of the thyroid gland gradually recovers. The thyroid scan may show a sparse and uneven image. In the recovery phase, the thyroid scan returns to normal. In a few patients, small nodules may remain in the thyroid gland.
5.Color Doppler ultrasonography
Ultrasound examination mainly shows enlarged thyroid volume, hypoechoic phase and blurred thyroid borders. The volume of the thyroid gland measured by ultrasound may decrease as the disease improves. Ultrasound examination is simple, non-invasive and can be repeated several times.
V. Other tests
1.Thyroid antibody
0TgAb or TPOAb negative or low titer. Increased titers of respiratory virus antibodies, which mostly disappear gradually after 6 months.
2.Thyroid biopsy
Fine needle aspiration cytology examination smear can be seen follicular cells, multinucleated giant cells, inflammatory leukocyte changes. The main purpose is to identify thyroid adenoma, adenocarcinoma, medullary carcinoma and Hashimoto’s thyroiditis.
3.CT examination
In the acute stage, CT scan shows irregular enlargement of the thyroid gland with focal hypodensity, which is not clear in the enhanced scan. The lesions were seen to be recurrent and migratory (improving on the affected side and occurring on the contralateral side) in the reviewed cases. On follow-up after treatment, the parenchymal density tended to be homogeneous in the CT images.
VI. Diagnosis
The diagnosis of typical subxiphoiditis is not difficult. The main clinical manifestations are enlargement of the thyroid gland, pain and tenderness, accompanied by systemic symptoms, a history of upper respiratory tract infection or fever before the onset of the disease, laboratory tests may include mild elevation of total white blood cells and neutrophils, markedly increased sedimentation, elevated CRP, elevated serum TT3, TT4, FT3, FT4 and decreased iodine uptake of the thyroid gland, a separation phenomenon, and a thyroid The thyroid gland is unremarkable or sparse on scan.
The diagnosis of the disease is based on.
1. enlargement, pain, hardness and tenderness of the thyroid gland, often accompanied by signs and symptoms of upper respiratory tract infection (fever, malaise, loss of appetite, enlarged cervical lymph nodes, etc.)
2. accelerated blood sedimentation.
3. suppressed thyroid uptake rate of 131I.
4. transient hyperthyroidism.
5, thyroid antibodies: negative or low titers of TgAb or TPOAb.
6, multinucleated giant cells or granulomatous changes on thyroid fine needle aspiration or biopsy. The diagnosis can be made if the above four items are met.
Differential diagnosis
For those with atypical clinical manifestations, it may lead to misdiagnosis and misdiagnosis, and needs to be differentiated from the following major diseases.
1. Upper respiratory tract infection: Patients with upper respiratory tract infection often have symptoms such as fever, headache, stuffy and runny nose, and cough. If the patient first develops symptoms such as throat discomfort and pain, and does not improve significantly after antibiotic or antiviral treatment, and also develops weight loss, panic and hand tremors, attention should be paid to exclude subluxation.
2, acute suppurative thyroiditis: acute bacterial infection, inflammatory reaction is obvious, the local skin of the thyroid gland may have redness, swelling, heat, pain, systemic symptoms and temperature rise, blood leukocytes and neutrophils are elevated significantly, serum T3, T4 and thyroid iodine uptake rate is normal, thyroid puncture can be extracted pus, antibiotic treatment effect is significant.
3. Cystic thyroid adenoma or adenoma-like nodule combined with acute hemorrhage: often occurs on the basis of the original thyroid disease, localized nodules in the thyroid gland, mild pressure pain, hard texture, normal blood sedimentation, CRP, serum T3, T4, thyroid iodine uptake rate, cool nodules or cold nodules on thyroid scan, liquid dark areas in the thyroid mass on ultrasound, dark red or coffee-like fluid can be extracted by thyroid puncture, and antibiotic treatment is effective. The pain will be relieved immediately after fluid extraction.
4.Thyroid cancer: About l0% of patients with subthyroiditis have localized enlargement of the thyroid gland with no other symptoms. It can be differentiated from other diseases. If necessary, thyroid aspiration cytology can be performed to help differentiate.
5. Graves’ disease: hyperthyroidism in combination with subarthritis has an acute onset and a short course, with mild to moderate hyperthyroidism and transient symptoms, no eye signs, no vascular murmur in the thyroid gland, and a scan of the thyroid gland showing sparse or no shadowing. In order to avoid misdiagnosis and misdiagnosis, thyroid scan should be performed to help differentiate patients who have hyperthyroidism symptoms within a short period of time, with obvious fatigue without proptosis or thyroid vascular murmur. For those who have been treated with oral antithyroid drugs and whose symptoms improve significantly in the short term or even develop hypothyroidism, attention should be paid to exclude subacute thyroiditis.
6. Subacute lymphocytic thyroiditis: no prodromal symptoms of viral infection, no thyroid pain or tenderness, few changes in viral antibody titers, mostly normal blood sedimentation, biopsy showing lymphocytic thyroiditis.
VIII. Treatment
Patients with mild symptoms do not require special treatment. Take non-steroidal anti-inflammatory and analgesic drugs, such as ibuprofen and indomethacin, etc. For those with heavy systemic symptoms, high fever, enlarged thyroid gland and obvious pressure pain, glucocorticoid therapy should be used. At present, oral prednisone is still the first choice clinically, 10mg each time, 3 times/d, obvious pain relief, 8-10 days to start reducing the drug, usually 5mg per week, the total course of treatment 2-3 months. In the initial treatment of hormone, the average blood sedimentation drops to normal in 2 weeks, and in some patients, the blood sedimentation can even drop to normal in 1 week of medication. The hormone treatment of subthyroiditis should follow the early use of medication, sufficient dose, slow reduction of medication, and sufficient course of treatment. It is believed that intra-thyroidal injection of dexamethasone for subxiphoiditis improves the signs and symptoms faster than oral prednisone. Local application and short duration can avoid various side effects of long-term systemic application of hormones. In recent years, there has been more experience with Chinese herbal medicine in the treatment of subxiphoid arthritis. For patients with recurrent and prolonged relapses, additional Chinese herbal medicine can be taken to help reduce symptoms, shorten the course of treatment, improve the efficacy and reduce relapses. In the case of hyperthyroidism, anti-thyroid medication is generally not required, and some patients may be given small doses of propranolol to slow their heart rate. If the disease is long, patients who are at risk of or have undergone hypothyroidism may be treated with additional thyroxine tablets as appropriate until function returns to normal (usually 3 months to 6 months). The occurrence of permanent hypothyroidism is seen.
IX. Prognostic evaluation
The disease is mostly self-limiting and can remit on its own, with a good prognosis. 90% of patients with remission have normalized thyroid function, and some patients may have recurrent disease, only about 5% to 10% of patients have permanent hypothyroidism and need lifelong thyroid hormone replacement therapy. Surgery is generally not required. However, surgery may be considered in the following cases: coexistence with other thyroid lesions, such as thyroid cancer, severe nodular goiter with obvious pressure symptoms, etc. In cases of diagnostic difficulties, surgical exploration should be performed and the surgical procedure should be decided based on the intraoperative rapid frozen section pathology.